Things You Must Know About DAC Cable

Fiber optic patch cable, also known as fiber jumper, is a fiber optic cable terminated with fiber optic connectors on both ends. And it is widely used in the connections between network equipment. In recent years, a kind of fiber optic patch cable which can transmit data at a high data rate with low cost is popular with data center users. That’s DAC cable or Direct Attach Cable, and this passage will focus on DAC cable’s overview, type and feature.

Overview of DAC Cable

Direct attach cable is a form of high speed cable with two connectors on either end which are in the form of optical transceiver module, such as SFP+, QSFP+ and so on, but they not real optical transceiver modules. Direct attach cable can support Ethernet, Infiniband, Fibre Channel and other protocols. And it is mainly used for the connection between switches, servers, routers in the interconnection application of racks. As a cost-effective solution in short reach applications, DAC is usually used in equipment distribution area (shown as the figure below).

Application of DAC Cable in Equipment Distribution Areas

Types of DAC Cable

Seen from the material of the cable, DAC can be classified into direct attach copper cable and active optical cable (AOC). Direct attach copper cable can either be passive or active, while AOC cable is always active. The following part will separately give an overview of passive direct attach copper cable, active direct attach cable and active optical cable.

Passive Direct Attach Copper Cable

Shown as the figure below, the connectors of passive direct attach copper cable contain no active components. The passive direct attach copper cable provides a direct electrical connection between corresponding cable ends and it can reach the transmission distance of 7m at a data rate of 10 Gbps or 40 Gbps with low power consumption.

Passive Direct Attach Copper Cable

Active Direct Attach Copper Cable

Compared with passive direct attach copper cable, the connectors of active direct attach copper cable contain active components, such as cable drive, to transmit and receive electric signals. Therefore, the active direct attach copper cable consumes more power. While these active components help to improve signal quality and provide a longer cable distance. For example, the active direct attach copper cable can reach the transmission distance of 15m at a data rate of 10 Gbps or 40 Gbps.

Active Direct Attach Copper Cable

Active Optical Cable

The material of AOC’s cable is fiber optic cable and the connectors of active optical cable contain active components, such as rear stage magnifying glass, laser driver and so on. As a result, the transmission distance of active optical cable is much longer than passive direct attach copper cable and active direct attach copper cable’s. Usually, the active optical cable can transmit signals up to 100m.

Active Optical Cable

Feature

From the content above, we can easily find that with different components inside connectors, different types of direct attach cables have different features. This part will give a detailed introduction about direct attach copper cable and active optical cable’s features.

For direct attach copper cable:

It supports higher data rates than traditional copper interfaces from 4 Gbps to 10 Gbps per channel.

It is interchangeable and hot swappable with fiber optical modules.

It is a cost-effective solution over optical transceivers and cables or short reach applications.

It supports multiple protocols, such as Gigabit & 10G Ethernet, 8G FC, FCoE, InfiniBand SDR, DDR & QDR.

For active optical cable:

It is an alternative to optical transceivers which eliminates the separable interface between transceiver module and optical cable.

Needing no equipment upgrades, it has a throughput of up to 40 Gbps with QSFP+; it weighs less than a comparable direct attach copper cable.

It is immune to electromagnetic energy because the optical fiber is a kind of dielectric (not able to conduct electric current).

Conclusion

DAC cable is a cost-effective, proven solution for interconnecting networking applications. It uses the same port as an optical transceiver, but with significant cost savings and power savings advantages in short reach applications. What’s more, the product is continuing to evolve to meet industry needs of higher data rates and densities with low power consumption.

Introduction to Fiber Breakout Cable

Fiber breakout cable is a kind of fiber optic cable that contains several single-core optic fibers inside one outer cable jacket, and those single-core optic fiber are also covered by jackets. The design of fiber breakout cable adds strength for ruggedized drops, but the cable is larger and more expensive. Fiber breakout cable is suitable for short riser and plenum applications and also for use in conduits, where a very simple cable run is planned to avoid the use of any splicebox or spliced fiber pigtails.

Structure of Fiber Breakout Cable

The structure of fiber breakout cable (shown as the following figure) ensures a long life of the cable. The fiber breakout cable is composed of outer jacket, threaded connection device, breakout fiber assembly (tight-buffered fiber surrounded by aramid yarns outer layer and jacket ), reinforcing component and ripcord. In order to handle more easily, there is a 900 um coating which is easy to be stripped in the cable. Both the PVC and plenum cables are rated for fire safety.

fiber breakout cable

Features of Fiber Breakout Cable
  • A fiber breakout cable can “break out”several fibers at any length. Therefore, in is necessary to code fiber breakout cable for easy identification.
  • Each fiber has its own jacket and aramid reinforced component. This makes fiber breakout cable convenient to use and each fiber is very strong and durable. The following figure shows different types of fiber breakout cable.

fibre breakout cable

  • Each fiber adopts tight buffer technology or semi-tight buffer technology, so fiber breakout cable has a good ability to resist stripping.
  • Each fiber of fiber breakout cable is reinforced individually. Therefore, fiber breakout cable can be divided into several individual fiber optic lines. In this way, it takes less time to connect the termination and there is no need for the patch panel.
  • Due to the use of Kevlar component with increased strength, fiber breakout cable is much heavier and larger than the telecommunication type of cable with same fiber count.
  • Fiber breakout cable is better than standard fiber optic patch cable, because it eliminates the need of a fiber optic ducting system. The cable is particularly effective when equipment stands in a large area, for example, several floors in a huge building.
  • Fiber breakout cable has a better economy. It can save a lot of labor when connected to the termination. Although a cable that has more fibers is more than what you actually need, it is a good option in case of damage during the connection to the termination or future expansion.
Application

Fiber breakout cable has a wide range of applications. It is suitable for short network design, such as LANs, data communication, video system and technology control environment. And fiber breakout cable is typically used in indoor applications: between the fiber optical distribution frame and the electronic equipment rack; between two electronic equipment racks. Some building environments require flame-retardant, non-toxic and smoke-free or flame-retardant with smoke and most fiber breakout cable can satisfy these requirements. And the cable is also suitable for pre-terminated cable assemblies. With a variety of designs and types, fiber breakout cable can meet the topological requirements in the hash environment. Fiber counts vary from single-core to 256. For installation which requires high strength, high reliability, maximum mechanical and environmental protection, fiber breakout cable is an ideal option.

Conclusion

Fiber breakout cable has good future prospects. With the trend of high-density in network communication, fiber breakout cable will play a more and more important role in network construction.

Introduction to Fiber Optic Pigtail

Fiber optic pigtail is a fiber optic cable that has an optical connector on one end and a length of exposed fiber on the other end. The connector side is used to link the equipment, while the other side is melted together with fiber optic cable. A fiber pigtail is single, short, usually tight-buffered. Technology of optical fiber fusion splicer is used during the process which can lower the insertion loss, that is, the end of the pigtail is stripped and fusion spliced to a single fiber of a multi-fiber trunk. Splicing of pigtails to each fiber in the trunk “break out” the multi-fiber cable into its component fibers for connection to the end equipment.

Fiber optic pigtail can have female or male connectors. Although single-fiber solution exists, female connectors could be mounted in a patch panel, often in pairs. In this way, they can be connected to endpoints or other fiber runs with patch fibers. In addition, male connectors can be used to plug directly into an optical transceiver.

Types of Fiber Optic Pigtails

As one type of fiber optic patch cable, fiber optic pigtail can be classified by different types of cables and connectors.

Fiber Optic Pigtails with Different Cable Types

Single-mode fiber optic pigtail is yellow. It transmits the optical signal with two types of wavelength, 1310nm and 1550nm. Accordingly, the transmission distance of single-mode fiber optic pigtail is 10km and 40km.

Multimode fiber optic pigtail is orange. It transmits the optical signal with the wavelength of 850nm. The transmission distance of multimode fiber optical pigtail is 5km and it is suitable for short distance transmission.

Simplex fiber optic pigtail is applied in one-way data transmission because the data is transmitted almost in one direction.

Duplex fiber optic pigtail can separately transmit and receive signals on two opposite directions at the same time.

Fiber Optic Pigtails with Different Connector Types

Here are illustration samples of the common ST/SC/LC/FC pigtails.

illustration sample

Some Other Types of Fiber Optic Pigtails

Bunch fiber optic pigtail adopts tight-buffered fibers with the cladding and cable jacket, widely used in transmission lines ans dense connection between the terminal equipment.

bunch pigtail

Ribbon fiber optic pigtail is characterize by its higher density of fiber. This is very important for the upstream applications which require high-density fiber cable.

ribbon pigtail

Waterproof fiber optic pigtail is produced strictly according to IEC standards. It is characterized by low insertion loss, high return loss, good interchangeability and repeat push-pull performance and it’s easy to use. Waterproof pigtail is equipped with strong jacket and waterproof sealed head connector which can be used in harsh environment.

waterproof pigtail

Conclusion

With the development of optical telecommunication network, a variety of optical fibers are widely applied in different occasion. And fiber optic pigtail is a great option for CATV, LANs, Gigabit data network testing, and some other fields.

Introduction to Fiber Optic Patch Cable

Fiber optic patch cable is a fiber optic cable terminated with fiber optic connectors on both ends. It has thick layer of protection and is commonly used to connect the optical transmitter, receiver, and the terminal box in fiber optic network. Fiber optic patch cable is also known as fiber optic patch cord, fiber optic jumper.

The fiber optic patch cable is constructed from the core, the cladding, the coating, strengthening fibers and the cable jacket. Transparency of the core permits transmission of optic signals with little loss over great distances; the cladding causes light to be confined to the core of the fiber; the coating’s low refractive index reflects light back into the core, minimizing signal loss; the protective cable jacket minimizes physical damage to the core and coating. And on both end, there are connectors. (shown in the following figure.) For multi-core cable, the core measures 50 um to 65 um in diameter, approximately the thickness of a human hair; while the core of single-core cable is 8 um to 10 um in diameter.

Fiber optic patch cable

Fiber optic patch cable is characterized by:

  • Low insertion loss
  • High return loss
  • Good repeatability
  • Good interchange
  • Excellent environmental adaptability.

There are various types of fiber optic patch cables and they can be classified mainly by the types of cables and connectors.

Fiber Optic Patch Cables with Different Cable Types

Single-mode fiber is generally yellow with a blue connector, and it has a longer transmission distance.

Multimode fiber is generally orange or grey with a cream or black connector, and it has a shorter transmission distance.

Armored fiber optic patch cable uses a layer to protect the fiber inside from being bitten or other damage.

Bend insensitive fiber optic patch cable is widely used in FTTH and it is not sensitive to stress and bending.

Mode conditioning patch cable is a kind of double multimode patch cable and has a small length of single-mode fiber at the beginning of transmission length.

Fiber Optic Patch Cables with Different Connector Types

Fiber optic patch cable can be terminated with various types of connectors, such as LC, SC, ST, FC, MTRJ, E2000, MU and MPO/MTP. In addition, the connectors on both end can be the same or different. Therefore, the following part will focus on different types of connectors.

LC Connector

LC connector has a push and latch structure, with plastic shell and accurate 1.25mm ceramic ferrule. LC connector is in small size and has good performance. It is very popular and widely used for dense installation.

LC connector

SC Connector

SC stands for Subscriber Connector or Square Connector or Standard Connector. It is a kind of push and pull connector. SC connector has a locking tab which can make accurate alignment through ceramic ferrule. It features low cost, simplicity as well as good durability and it’s commonly used in data communication and telecommunication fiber optic market.

SC connectoe

ST Connector

ST stands for Straight-Tip and ST fiber optic cable has a bayonet rotary locking mechanism. There is a 2.5mm diameter ferrule on ST connector, the same as SC connector’s.

ST connectoe

FC Connector

FC connector is a kind of bolt type connector. FC stands for Fixed Connector which has a metal shell and bolt connection structure. The ferrule and sleeve on FC connector are the same with SC connector’s.

FC connector

MT-RJ Connector

MT-RJ connector which is developed from MT and RJ connectors. MT-RJ stands for Mechanical Transfer Registered Jack. There are plastic cover and ferrule on MT-RJ connector and it is characterized by the connection with two fibers, that is, two fibers are connected in one MT-RJ connector. MT-RJ connector has female type and male type. The difference between these two types is that the male type is constructed with two ferrules on one connector.

MT-RJ connector

E2000 Connector

E2000 connector has a spring-compressed valve and push-pull locking device to protect ferule from dust and wear. When inserting the connector, push-pull locking device will fully lock; when pulling it out, the spring-compressed valve will close automatically.

E2000 connector

MU Connector

MU connector has a plastic shell and push-pull locking mechanism. MU connector is small in size and has a ferrule with 1.25mm diameter. And MU connector is used in advanced optical transmission and exchange, user system or high speed data application.

MU connector

MPO/MTP Connector

MPO connector is high-density fiber optic connector and uses precise modeled MT ferrule. In single MPO patch cable, there are several fiber counts, such as 12 fibers, 24 fibers and 36 fibers. MTP is the optimized version of MPO. MTP adopts push-pull locking mechanism and it’s easy to insert and pull out.

MTP connector

Fiber optic patch cables are widely used in various fields, such as the connections to CATV (Cable Television), telecommunication networks, computer fiber networks and fiber test equipment. Applications include communication rooms, FTTH (Fiber to The Home), LAN (Local Area Network), FOS (fiber optic sensor), Fiber Optic Communication System, Optical fiber connected and transmitted equipment, Defense combat readiness, etc.

Introduction to Fiber Optic Cable

Fiber optic cable uses one or more optical fibers to transmit large amounts of information at the speed of light, which plays an important role in optic communication network. As a new generation of transmission medium, fiber optic cable has a great improvement in the quality, safety, reliability, transmission speed and transmission capacity. Besides, the transmission distance of fiber optic cable has achieved dozens of km, which is the first option to be used in large-scale network.

Fiber optic cable consists of the core, the cladding, the coating, strengthening fibers and the cable jacket (shown in the following figure.).

Fiber Optic Cable

Core: The core is characterized by its diameter and it is a cylinder of glass or plastic that runs along the fiber’s length. And it is the light transmitting region of the fiber.

Cladding: It is the first layer around the core. The cladding causes light to be confined to the core of the fiber by total internal reflection at the boundary between the two.

Coating: It is the first non-optical layer around the cladding. The coating typically consists of one or more layers of a polymer that protect the silica structure against physical or environmental damage.

Strengthening Fibers: These are used to enhance the ability of cable to bear the load during the laying. Generally metallic or non-metallic fibers. The materials generally are metallic or non-metallic fibers.

Cable Jacket: This is the outer layer of any cable. The cable jacket is characterized by flame-retardant, damp-resistant, voltage-endurance and corrosion resistant and the main function of it is to protect the fiber optic cable.

Nowadays, different applications need different types of fiber optic cables which can be classified by different aspects.

Transmission Mode

Single-mode fiber cable: It allows only one mode of transmission. Because of this, the light can only be transmitted along the fiber core, completely avoiding optical dispersion and waste of energy. And single-mode fiber cable features low insertion loss and high return loss, good ability of adaptation to the environment, high data transfer rate and supporting simplex or duplex connector type. It is typically used in network connection which needs long distance transmission and high bandwidth.

Multimode fiber cable: It allows multiple modes of light transmission. Because of this, multimode fiber cable has higher “light-gathering” capacity. However, the quality of the signal is reduced over long distance for high dispersion and attenuation rate with this type of fiber. So multimode fiber cable is mostly used for communication over short distances, such as within a building or on a campus.

Transmission Way

Simplex Cable: It consists of a single strand of glass or plastic fiber. The data is transmitted almost in one direction, so it is applied in one-way data transfer.

Duplex Cable: It consists of two strands of glass or plastic fibers. Each fiber strand has independent coatings that are linked together by a thin layer of coating material. It is most used where separate transmit and receive signals are required, that is, one strand transmits in one direction while the other strand transmits in the opposite direction.

Core Count

Single-core Fiber: It is designed to carry light only directly down the one core and it is often used in household.

Multi-core Fiber: It consists of more than one core. It’s a revolutionary new approach to engineer a fiber for high capacity applications and it is often used in the trunk.

Fiber Road Laying

Pipe Fiber Optic Cable: It is used in the access network or user resident network. Pipeline laying is generally in urban areas and the environment is better, so there is no special requirement for cable sheath.

Direct-buried Fiber Optic Cable: It is especially designed to be buried under the ground without any kind of extra covering, sheathing, or piping to protect it. Most direct-buried cables are built to specific tolerances to heat, moisture, conductivity, and soil acidity.

Aerial Fiber Optic Cable: It is used on a pole. Aerial fiber optic cable laying can make use of the existing pole line, saving construction cost and shortening the construction period. And it can adapt to a variety of natural environment.

Submarine Cable: It is wrapped with insulating materials, laying at the bottom of the sea, to set up a telecommunication transmission between countries.

Environment & Situation

Indoor Cable: It is used for indoor environment and mostly adopts tight set of structure. Its characteristics are soft and flame-retardant which can satisfy the need of indoor wiring.

Outdoor Cable: It is used for outdoor environment. And it can bear the climate change, prevent the infiltration of water, resist the ultraviolet radiation and resist other forces.

Accompanied by the continuous advancement of network technology, fiber optic cable constantly participates in the construction of telecommunications networks, the construction of the national information highway, Fiber To The Home (FTTH) and other occasions for large-scale use. Although fiber optic cable is still more expensive than other types of cable, it can support today’s high-speed data communications because it eliminates the problems of twisted-pair cable. Therefore, fiber optic cable is still a good choice for people.

Introduction to Multimode Fiber Optic Cable

Multimode fiber optic cable is commonly used in data transmission. It has a larger diameter core with a common diameters in the 50 to 100 micron that allows multiple modes of light transmission. Because of this, multimode fiber optic cable has higher “light-gathering” capacity. However, the quality of the signal is reduced over long distance for high dispersion and attenuation rate with this type of fiber. Compared to single-mode fiber, the multimode fiber bandwidth-distance product limit is lower. So it is mostly used for communication over short distances, such as within a building or on a campus. There are many types of multimode fiber optic cables and different type has different transmission rate.

Multimode fiber cable is described by their core and cladding diameters. It is usually 50/125 um and 62.5/125 um in construction. The 50/125 um multimode fiber has a core size of 50 um and a cladding diameter of 125um; while the 62.5/125 um multimode fiber has a core size of 62.5 um and a cladding diameter of 125um (shown as the figure). The transition between the fiber core and the cladding should be sharp, which is called a step-index profile, or a graded-index profile. These two types have different dispersion characteristics, so they have different effective transmission distance. Multimode fibers can be constructed with graded or step-index profile, and those fibers with graded-index are better in accuracy and performance. The specified size 50/125um and 62.5/125um include the diameter and the cladding. The cladding limits the light to the core because of its lower refractive index. The cable construction is shown in the following figure and indicates the cable core, cladding and outer jacket diameters.

multimode fiber cable
Types of Multimode Fiber Optic Cables

Multi-mode fibers are described using a system of classification determined by the ISO 11801 standard — OM1, OM2, and OM3 — which is based on the modal bandwidth of the multimode fiber. OM4 (defined in TIA-492-AAAD) was finalized in August 2009 and was published by the end of 2009 by the TIA. The letters “OM” stand for optical multimode.

OM1

OM1 specifies 62.5μm cable and has been the most popular multimode fiber choice throughout the 1980’s and 1990’s. By the early 21st century, it has become the most widely used multimode fiber. However, compared to other multimode fibers, it has the lowest data transmission rate and the shortest transmission distance. The performance of OM1 (62.5 μm) fiber has reached its peak at this time.

OM1

OM2

OM2 specifies 50-micron cable. For many years, 62.5/125 μm (OM1) and conventional 50/125 μm multimode fiber (OM2) were widely deployed in premises applications. These fibers easily support applications ranging from Ethernet (10 Mbit/s) to gigabit Ethernet (1 Gbit/s) which are not suitable though for today’s higher-speed networks. And because of their relatively large core size, they were ideal for use with LED transmitters.

OM2

OM3

OM3 is laser optimized multimode fiber. This technology allows the laser transmission system to use multimode optical fiber for the first time without the use of mode adjustment cables. OM3 together with new low-cost vertical cavity surface emitting laser realizes 10G transmission.

OM3

OM4

OM4 fiber has been on the market since 2005 and it is the optimized product of OM3 fiber. OM4 fiber and OM3 fiber are fully compatible with each other, and both of them use the same light green outer jacket. Like OM3, OM4 was designed specifically to work with VSCEL. But the difference is that OM4 has a longer transmission distance of 550m in 10G transmission while OM3’s is 300m in the same condition. In addition, the effective mode bandwidth of OM4 is 4700MHz.km which is more than double that of OM3 (the effective mode bandwidth is 2000 MHz.km of OM3). And OM4 has a greater advantage in transmission distance ans cost control.

OM4

Followings are the tables for types and specifications of multimode fiber optic cables:

Types

Types

Specifications

Specifications

The type of multimode fibers is up to hundreds and different different types have different transmission constant and rate which result in narrow bandwidth, high dispersion and high loss of fiber optic. Therefore, multimode fiber cable is only suitable for middle short transmission distance and fiber optical communication system with small capacity.